No updates for some time but now there are. Actually I changed sound cards again but more on that on some later post. I still haven't replaced the power supply. I did install the 350W Nexus to another case to try how easy it is to replace AT power supply with ATX.
And there are many problems. First I needed to drill new holes so I could install the power supply correct way (fan down so it works like it should). Second the ATX power supply has too many molex (and SATA) cables and they are way too long. So it is a pain to hide all the wires. And possibly impossible on some cases.
Then you need the ATX to AT converter and that makes the motherboard power cable even longer. And those converter cables are badly designed. The soft power wires on them are too short since they need to be connected to the power switch on front of the case. So all those cables are just a mess that will affect ventilation for sure. And makes everything hard to reach.
But it gets even worse. Those Nexus PSUs are actually manufactured by FSP group. That wouldn't matter otherwise but they have that glue that turns conductive when aging. And bad caps. And the unused 400W unit was manufactured in 2006 and it still had bad caps! I'm in the process of restoring the 400W unit since it was unused. I've managed to remove the glue but I need to replace the capacitors. But I won't trust those Nexus PSUs enough to use them in this machine. So I recommend to service the old AT PSU if possible or use a new ATX power supply. Forget old ATX power supplies. Even the "quality" ones can be time bombs. And as mentioned above, there will be all sorts of cabling issues fitting the ATX power supply in AT case.
Edit: I forgot to mention one more problem. When using ATX power supply as AT replacement and the power is off, the ATX power supply is in stand by mode even though the motherboard is not. One great thing about AT PSUs is that there is no useless and possibly dangerous stand by mode. Power is on only when you need it and want it.
But I still need 25A on the 5V rail so I need new power supply (actually I think I could use linear voltage regulator to power McCake from 12V rail. Then I would not need new PSU). I just recently found used Corsair VENGEANCE 650M. It is a modern 650W power supply that can supply 25A on 5V rail. It has Japanese capacitors so that should be good as well. It is modular so I don't have to use all those completely unnecessary SATA power cables. The model I have is RPS0049. There seems to be different models under the same name. I don't have that single/multi rail switch as seen on some pictures. This is what I have and take a look what I did to it. This is a good time to warn that PSUs are dangerous and should not be messed with. I was careful and still managed to get a shock from the 400W Nexus.
I converted it to AT power supply! (It can be quite easily converted back to ATX if necessary).
1. I added second power switch so it works just like AT power supply would. Those soft power leads on the adapter can be just connected together and covered with tape. The actual switch on the pictures was for testing purposes only. Naturally it will be connected to the power switch on the case. I didn't remove the power switch on the back of PSU. Power switch that does nothing can be dangerous and removing it would just have left a hole that would have to be covered with something. So there are now two power switches but the one on the back can simply be left on. I didn't even have to drill a new hole for the AT power cable. It fit to the same hole as the motherboard power cable.
2. I added linear voltage regulator to provide -5V. There was a perfect spot where to glue it. See that very small piece of board with regulator and two capacitors. -12V and ground wires are soldered under the PSU PCB since it was the easiest. The -5V output wire goes to the cable sleeve with all the other ATX power wires. So the -5V mod is almost invisible!
The modified PSU is tested and now it is time to install it to the DX4 system. I finally decided to switch back to the original case so I'll do that also. But since I now need to remove the motherboard from the old case, this is finally a good time to test all those CPUs I have waiting.